Water turbine operation method and system

ABSTRACT

When a water turbine is shifted from phase modifier operation to electric power generator operation, a guide vane is opened to a predetermined limited extent after a by-pass valve is wide opened and thereafter a main valve is opened while the guide vane is opened following the opening of the main valve by detecting the hydraulic pressure within a casing.

United States Patent Oishi et al. 1451 Apr. 25, 1972 WATER TURBINEOPERATION [56] References Cited METHOD AND SYSTEM UNITED STATES PATENTS[72] inventors: Asao Oishi; Takao Doi; Yoshimasa Ueno, 1,474,086 11/1923Poebing ..415/1 all of Hitachi, Japan 3,030,070 4/1962 Krauss .....415/l 3,264,485 8/1966. Naganuma et al... .....415/1 [73] Assgnee- Japan3,309,057 3/1967 Tonooka ..415/1 22 Filed: Man 6 1970 3,372,645 3/l 968Willi ..4l 5/1 3,533,709 10/1970 Willi ..4l5/l 21 Appl. No.2 17,2015 1Primary Examiner-C. J. Husar Attorney-Craig, Antonelli & Hill [30]Foreign Application Priority Data Mar. 10, 1969 Japan ..44/1s4ss [571ABSTRACT l When a water turbine is shifted from phase modifier operation[52] US. Cl ..4l5/l, 415/13 to electric power generator operation, aguide vane is opened [51] Int. Cl. ..F0ld 17/00 o a p e ermin limi ed exn after a y-p valve i i 58 Field of Search ..415/1, 13 Opened andthereafter a main valve is Opened while the guide vane is openedfollowing the opening of the main valve by detec ting the hydraulicpressure within a casing.

2 Claims, 4 Drawing Figures PATENTED fiPR 2 5 m2 SHEET 2- UF 4 Al SShims QmmSQm Qmewms \A ib 4 mmbmmwmm WERE qwmo E86 53 @506 535 II mwwsd5 3 aims \A in Qmmsqu 53 INVENTOR S ASA!) aISHI, TAkAo D013 and Y MAsAATTORNEYJ PATENTEUAPMS IHYZ 8,658,436

SHEET 3 0? 1 W FIG. 3 29 28 INVENTORS ASAO OISHI. TAKAD DUI andYOSIIIMASR MEN WATER TURBINE OPERATION METHOD AND SYSTEM The presentinvention relates to a method and system for shifting from phasemodifier operation to electric power generator operation of waterturbine in a hydroelectric plant having a few to several generators.

Generally water turbine generators are not used only for generatingelectric power. When the power consumption is relatively less, the waterturbine generators are driven as rotary phase modifiers instead of beingshut down so as to improve the power factor of the power transmissionsystem. These water turbine generators must be immediately shifted fromphase modifier operation to electric power generator operation when theload of the running generators is suddenly increased.

When the water turbine generators are driven as phase modifiers inparallel with the transmission system, the resistance of the waterturbine runner may be reduced by placing it in the compressed air inorder to minimize the input as much as possible to the water turbinegenerators which are driven as phase modifiers. More particularly, thewater in the runner casing is forced down into the draft tube by forcingthe air under pressure into the casing so that the runner may be placedin the compressed air, thereby decreasing the runner rotation resistanceand reducing the input to the phase modifiers.

When the water turbine generators are shifted from phase modifieroperation to electric power generating operation, the air in the runnerchamber for lowering the water level therein must be discharged from thedraft tube. For this purpose, the prior art opens an exhaust valveassociated with the water turbine casing so as to completely dischargethe air from the draft tube and thereafter open gradually the guide vaneafter the bypass valve and the main valve have been fully opened therebyshifting the water turbine generators to the power generating operation.Therefore, there is a long time interval between the step fordischarging the air and the step of starting the power generation sothat the water turbine generators cannot be shifted immediately to thepower generating operation in response to the sudden load increase.

The longer discharge time required for discharging the compressed airand the longer time interval during which the water turbine runner isunder water mean that the resistance to the rotation of the waterturbine runner is high and lasts for a considerably long time.Therefore, the power loss of the motor for rotating the water turbinerunner is increased and the power of the transmission system isabnormally reduced.

In view of the above, the present invention has its object to provide awater turbine control method capable of shifting water turbines toelectric power generating operation in a very effective manner therebyreducing the shifting time and the power loss.

In brief, according to the present invention, when the water turbinewhich gas been driving as a phase modifier is shifted to the electricpower generating operation, a by-pass valve is first opened and at thesame time an exhaust valve for discharging the compressed air forlowering the water level in a casing is opened. After the by-pass' valvehas been fully opened, the ex haust valve is closed while a guide vaneis opened to a limited smaller degree. Thereafter a main valve isstarted to open and the guide vane is completely opened before the mainvalve is completely opened. The degree of opening of the guide vanerelative to the degree of opening of the guide vane relative to thedegree of opening of the main valve is controlled in response to thehydraulic pressure within the casing.

FIG. 1 is a schematic partial sectional view of a water turbineembodying the present invention; the water turbine being illustrated asbeing driven as a phase modifier;

FIG. 2 is a timing diagram for explanation of actuation of various partsthereof;

FIG. 3 is a schematic .view for explaining the controlling I system inaccordance with the present invention; and

FIG. 4 is a block diagram for explaining the system of the presentinvention.

A water turbine generator 1 may be used as a motor for rotating thewater turbine, when required. Reference numeral 2 designates a waterturbine casing; 3, guide vanes; 4, a draft tube; and 5, a main valvedisposed in a connection between a steel penstock 7 and the casing 2.The penstock 7 and the easing 2 are intercommunicated with each other bya by-pass 17. Reference numeral 6 designates a by-pass valve of thebypass 17; 8, a tail water reservoir; 9, a water turbine runner; 10, avalve interposed in an air pipe 16 for forcing the compressed air froman air compressor 13 into a water turbine runner chamber 18; 11, anexhaust valve for discharging the compressed air from the runner chamber18; 12, a water level detecting device for detecting the water level inthe runner chamber 18 which is forced down under the force of thecompressed air; and 14, a suction pipe for supplying the air into thedraft tube 4 where the negative pressure is produced in operation. Theair supply pipe 16 is branched into pipes 16 and 16" for supplying theair into the runner chamber 18 and the suction pipe 14 respectively fromthe air compressor 13 by suitably operating the valves 19 and 20 of thepipes 16' and 16". A servomotor 15 is provided for opening and closingthe main valve 5. Draft tube 4 is communicated with casing 2 through apiping 21 having a feed valve 22. Water pressure detecting instrument 23is fixed to the casing 2 for detecting the pressure within the casing 2through a hole 36 (See FIG. 3).

Referring to FIG. 3, the water pressure detecting instrument 23comprises a cylinder 27, a piston 24 for slidable movement in thecylinder 27, a spring 26 for normally biasing the piston 24 downwardlywith a suitable force withstanding the water pressure within the casing2 and a piston rod 25 adapted to move in unison with the piston 24 andhaving a contact 28 fixed to the free end thereof. A contact 29 isdisposed so as to oppose the contact 28 so that the contact 28 maycontact with the contact 29 depending upon the movement of the piston 24in response to the water pressure within the casing 2. The contact 29 iselectrically coupled through lead wires 30 to a servomotor 31 foropening or closing the guide vane 3. An electromagnet valve 23 isdisposed in a pipe 32 for feeding the oil under pressure for opening theguide vane 3. The free end of a piston rod 34 of the servomotor 33 isdrivingly coupled to a guide ring 35 which in turn is connected to alever (not shown) for operating the guide vane 3.

Referring back to FIG. 1, when the water turbine generator 1 isoperating as a motor for phase modification, all of the main valve 5,the guide vane 3, the valve 10 and the exhaust valve 11 are closed whilethe feed valve 22 is opened so that the tail water in the reservoir 8 isforced into the casing 2, thereby maintaining the water pressure in thecasing 2 at a suitable level and also feeding the water in the amountequivalent to the amount of the leakage of water from the guide vane 3.In the runner chamber 18, a desired water level is maintained byintroducing therein the compressed air from the air compressor 13 and bythe water level measuring instrument 12, so that the runner 9 isrotating in the compressed air. The water leaking from the guide vane 3is used for cooling this rotating runner 9. It is noted that the valves19 and 20 are not necessarily closed.

When the water turbine generator is shifted from its phase modifieroperation to power generation, the feed valve 22 is closed in responseto the shift instruction and the by-pass valve 6 starts to open. Theexhaust valve 11 for exhausting the compressed air within the waterturbine chamber 18 is opened and the input of the phase modifier isinterrupted. When the by-pass valve 6 is fully opened at the timeindicated by the line a in FIG. 2, the exhaust valve 11 is closed whilethe guide vane 3 is opened to a predetermined degree. In this case,water pressure of the steel penstock becomes substantially equal to thatin the casing 2 because the by-pass valve 6 is fully opened. There is nosudden increase in water pressure in the casing 2 so that the casing 2may be well protected. Since the water is supplied as leaking water fromthe guide vane 3, the closure of the feed valve 22 may be compensated.It is important that the opening area of the guide vane 3 at its limitedopening position is smaller than the opening area of the by-pass valve 6at its fully opened position because when said area of the guide vane 3is larger than said area of the by-pass valve 6, the water pressurewithin the casing 2 becomes exceedingly lower than that in the steelpenstock 7 and finally becomes the negative pressure so that thecompressed air within the water turbine chamber 18 is sucked into thecasing 2, thereby causing the vibrations and noises when the generatoris shifted to the power generation. In view of the above, special caremust be taken so as to suitably regulate the water pressure within thecasing 2. Therefore, the opening area of the guide vane 3 at its limitedopening position mustbe smaller than the opening area of the by-passvalve 6 at its fully opened position and it is preferable that theopening area of the guide vane 3 at its limited position be increased asmuch as possible within the opening area of the by-pass valve 6 at itsfully opened position since it serves to drive the runner toward thewater turbine. Upon opening the guide vane 3 to its limited openingposition described hereinabove, the water pressure within the casing 2may be maintained at a suitable level while the water under pressure isflowing into the runner chamber 18 so as to facilitate the rotation ofthe runner 9 in the direction of the water turbine power generation. Asdescribed hereinbefore,

the compressed air within the water turbine chamber 18 has beencompletely exhausted until the by-pass valve 6 is fully opened so thatthe runner chamber 18 is filled with water, but not to the full extent.Therefore upon rotation of the runner 9 in the direction of the waterturbine, the phase modifier would consume a large amount of powerbecause of the resistance from the water, but the input to the phasemodifier is interrupted and the guide vane 3 is partially opened evenwhen the input interruption is somewhat delayed as shown in FIG. 2, sothat the power consumption may be reduced, thereby preventing the excessdecrease in power in the transmission system. The runner has a force forcontinuing its rotation by its own inertia so that its r.p.m. will notbe exceedingly reduced. The small amount of the compressed air remainedin the water turbine chamber 18 is mixed with the water and turned intoair bubbles and discharged through the draft tube 4 into the tail waterreservoir 8 so that the operation is not adversely affected. At the timeindicated by the line b in FIG. 2 when the guide vane 3 is opened to itsabove described limited opening position. the input to the phasemodifier is shut off and the runner 9 can rotate only by the water fromthe guide vane 3 at its above described limited opening position.

At the time indicated by the line b in FIG. 2, the conditions foropening the main valve are fulfilled. But when the main valve 5 isimmediately opened after the guide vane 3 is opened to said limitedopening position, the vibrations will be caused because the waterpressure within the casing 2 has not been stabilized sufficiently. [t istherefore necessary that the main valve 5 is opened after the waterpressure within the casing 2 has been sufficiently stabilized. This canbe accomplished by use of a time limit relay or the like.

The water pressure within the casing 2 is increased after the by-passvalve 6 has started to open as shown in FIG. 2, but it is once decreasedwhen the guide vane 3 is started to open to its limited openingposition. Thereafter the water pressure is increased again upon openingof the main valve 5. The main valve 5 is opened at a constant speed sothat the water pressure within the casing 2 is increased accordingly.When the pressure within the casing 2 reaches a predetermined level, thewater pressure detecting instrument 23 fixed to the casing 2 is actuatedso that the guide vane 3 which has been in said limited opening positionstarts to open further. More specifically when, the water pressuredetected through the hole 36 formed through the casing 2 reaches apredetermined level, the piston 24 is caused to move upwardly againstthe spring 26 so that the contacts 28 of the piston rod 25 contact withthe contacts 29, thereby energizing the electromagnet valve 31 so as toopen it. Consequently, the oil under pressure is forced through the pip32 so that the servomotor 33 is actuated so as to open the guide vane 3.That is, the actuation of the servomotor 33 causes the guide ring 35 toopen the guide vane 3.

Upon starting of the opening of the guide vane 3, the water pressurewithin the casing is reduced, but it is dangerous that the waterpressure within the casing 2 is reduced because of the above describedreasons. Therefore, upon reduction in the water pressure within thecasing 2, the piston 24 of the water pressure detecting instrument 23moved downwardly under the force of the spring 26 so that the contacts28 and 29 are opened. Therefore the electromagnet valve 31 isdeenergized so as to close so that the servomotor 33 is deactivated,thereby stopping the guide vane opening operation. But the main valve 5continues to open so that the hydraulic pressure within the casing 2 isrestored. When the water pressure rises in excess of said predeterminedlevel, the water pressure detecting instrument 23 is actuated again.Thus, the above described water pressure adjustment operations arecycled so as to protect the casing 2 until the guide vane 3 is fullyopened at the time indicated by the line e in FIG. 2.

At the time a when the guide vane 3 at its said limited opening positionstarts to open further, the incoming generator is operated in parallelwith the transmission system. At this time, the flow of water into therunner chamber 18 form the guide vane 3 is sufficient enough to rotatethe runner so that when the generator is operated in parallel with thetransmission system, the latter is not adversely affected.

From the above, it will be understood that in response to theinstruction os shifting the generator to the generation from the phasemodification, the generator may be set in its ac generation until theby-pass valve 6 and the main valve 5 are opened, so that the timerequired for shifting is much reduced. The r.p.m. of the runner 9 is notexceedingly reduced during the shift. The power consumption of the phasemodifier is reduced and the system exhibits no abnormal decrease inpower.

The present invention has been so far described with particularreference to one illustrative embodiment thereof, but it will beunderstood that variations and modifications can be effected withoutdeparting from the true spirit of the present invention as describedhereinabove and as defined in the appended claims.

What is claimed is:

l. A water turbine control method comprising the steps of closing a feedvalve for supplying water so as to compensate the leakage of water froma guide vane in response to the instruction for shifting to acgeneration a water turbine which is running for phase modification,

opening a by-pass valve to full extent,

opening an exhaust valve for exhausting the compressed air from a runnerchamber,

shutting off the input to the phase modifier,

closing said exhaust valve when said by-pass valve is fully opened,

opening said guide vane to the maximum extent within the opening area ofsaid by-pass valve when it is fully opened, starting to open a mainvalve after said guide vane has been opened to a predetermined degree,

detecting the water pressure increase within a casing due to the openingprocess of said main valve so that when said water pressure reaches apredetermined level, said guide vane is started to open to the fullextent from said partial opening,

detecting the variation in water pressure within said casing due to thecontinuation of said opening process of said main valve so as to havesaid guide vane opening operation follow said guide vane to its fullopening degree before said main valve is fully opened, and

connecting a generator in parallel with a transmission system when saidguide vane has started to further open to its full opening degree fromsaid opening of said predetermined degree.

2. A water turbine operation system for a plurality of water turbineseach comprising means for detecting the water pressure within a waterturbine casing, a main valve for opening and closing a penstockconnected to the inlet of said casing, a by-pass for communicating saidcasing with said penstock by by-passing said main valve, a by-pass valveof said by-pass and a guide vane at the inlet of a water turbine runner,said plurality of water turbines being drivingly coupled to respectivegenerators which serve also as phase modifiers, said operation systemcomprising:

means for driving means for closing in response to an instruction forshifting said water turbine in phase modifier operation to the electricpower generating operation, a water feed valve which supplies water forcompensating the water leaking from said guide vane, means for openingsaid by-pass valve to the full opening, means for opening an exhaustvalve for exhausting from a runner chamber the compressed air, and meansfor interrupting the input to phase modifiers; means for actuating inresponse to a signal representative of the full opening of said by-passvalve, means for closing said exhaust valve and means for opening saidguide vane to the limited opening as large as possible within the fullopening of said bypass valve; means for opening said main valve inresponse to a signal representative of the completion of said guide vaneopening to said limited opening; means for detecting the increase inwater pressure within said casing due to said opening of said main valveso as to open said guide vane from said limited opening to the fullopening, said guide vane opening being controlled in response to thevariation in water pressure within said casing due to the continuousmain valve opening step so as to follow said main valve opening step,said guide vane opening being accomplished prior to said main valvebeing fully opened; and means for connecting in response to a signalrepresentative of limiting, opening and disengagement of said guide vanesaid generators in parallel with a transmission system.

1. A water turbine control method comprising the steps of closing a feedvalve for supplying water so as to compensate the leakage of water froma guide vane in response to the instruction for shifting to acgeneration a water turbine which is running for phase modification,opening a by-pass valve to full extent, opening an exhaust valve forexhausting the compressed air from a runner chamber, shutting off theinput to the phase modifier, closing said exhaust valve when saidby-pass valve is fully opened, opening said guide vane to the maximumextent within the opening area of said by-pass valve when it is fullyopened, starting to open a main valve after said guide vane has beenopened to a predetermined degree, detecting the water pressure increasewithin a casing due to the opening process of said main valve so thatwhen said water pressure reaches a predetermined level, said guide vaneis started to open to the full extent from said partial opening,detecting the variation in water pressure within said casing due to thecontinuation of said opening process of said main valve so as to havesaid guide vane opening operation follow said guide vane to its fullopening degree before said main valve is fully opened, and connecting agenerator in parallel with a transmission system when said guide vanehas started to further open to its full opening degree from said openingof said predetermined degree.
 2. A water turbine operation system for aplurality of water turbines each comprising means for detecting thewater pressure within a water turbine casing, a main valve for openingand closing a penstock connected to the inlet of said casing, a by-passfor communicating said casing with said penstock by by-passing said mainvalve, a by-pass valve of said by-pass and a guide vane at the inlet ofa water turbine runner, said plurality of water turbines being drivinglycoupled to respective generators which serve also as phase modifiers,said operation system comprising: means for driving means for closing inresponse to an instruction for shifting said water turbine in phasemodifier operation to the electric power generating operation, a waterfeed valve which supplies water for compensating the water leaking fromsaid guide vane, means for opening said by-pass valve to the fullopening, means for opening an exhaust valve for exhausting from a runnerchamber the compressed air, and means for interrupting the input tophase modifiers; means for actuating in response to a signalrepresentative of the full opening of said by-pass valve, means forclosing said exhaust valve and means for opening said guide vane to thelimited opening as large as possible within the full opening of saidby-pass valve; means for opening said main valve in response to a signalrepresentative of the completion of said guide vane opening to saidlimited opening; means for detecting the increase in water pressurewithin said casing due to said opening of said main valve so as to opensaid guide vane from said limited opening to the full opening, saidguide vane opening being controlled in response to the variation inwater pressure within said casing due to the continuous main valveopening step so as to follow said main valve opening step, said guidevane opening being accomplished prior to said main valve being fullyopened; and means for connecting in response to a signal representativeof limiting, opening and disengagement of said guide vane saidgenerators in parallel with a transmission system.